title: Poly(azobenzene acrylate-co-fluorinated acrylate) spin-coated films: influence of the composition on the photo-controlled wettability.
abstract: The wetting properties of spin-coated films of copolymers based on azobenzene and fluorinated units have been investigated. The copolymers, denoted as poly(Azo-co-AcRf6), have been synthesized by free-radical polymerization of different proportions of acrylate monomers bearing either an azobenzene group or a semifluorinated side chain. The UV-visible spectroscopy analysis of the different spin-coating films through a cycle of UV and visible light irradiation indicates the reversible trans-cis isomerization of azobenzene groups. Simultaneously, atomic force microscopy shows that surface roughness does not exceed 1 nm. Advancing and receding contact angles of water and diiodomethane have been measured before and after UV photoirradiation of the different surfaces. In particular, a decrease in the advancing contact angles has been observed upon trans-cis isomerization of azobenzene groups. Switching variations up to 50° have been evidenced without any introduction of surface nanoroughness. Surface free-energy evaluations have been deduced from these measurements, including dispersive and polar components. The results show that, through surface composition and UV photoirradiation, a large range of surface free-energies can be obtained, from 7 to 46 mN·m(-1).
authors.affiliation: Laboratoire de Physicochimie des Polymères et des Interfaces (LPPI, EA 2528), Institut des Matériaux, Université de Cergy-Pontoise, 5 mail Gay-Lussac Neuville/Oise, 95000 Cergy-Pontoise Cedex, France.
authors.forename: Sanae
authors.initials: S
authors.lastname: Abrakhi
authors.forename: Sébastien
authors.initials: S
authors.lastname: Péralta
authors.forename: Odile
authors.initials: O
authors.lastname: Fichet
authors.forename: Dominique
authors.initials: D
authors.lastname: Teyssié
authors.forename: Sophie
authors.initials: S
authors.lastname: Cantin